What is the molecular geometry of SF_4?

• A. Square planar
• B. See-saw
• C. Trigonal bipyramidal
• D. Tetrahedral

Answer: (B)

Verified step by step guidance

1. Step 1: Determine the Lewis structure of SF_4. Sulfur (S) is the central atom bonded to four fluorine (F) atoms. Count the total valence electrons: Sulfur has 6 valence electrons, each fluorine has 7, so total electrons = 6 + 4×7 = 34 electrons.
2. Step 2: Draw single bonds between sulfur and each fluorine atom, using 8 electrons (4 bonds × 2 electrons each). Distribute the remaining electrons to complete the octets of the fluorine atoms first.
3. Step 3: After completing fluorine octets, place any remaining electrons on the sulfur atom. Sulfur will have one lone pair in addition to the four bonding pairs with fluorine.
4. Step 4: Use the VSEPR theory to predict the molecular geometry. With 4 bonding pairs and 1 lone pair, the electron pair geometry is trigonal bipyramidal, but the molecular shape (ignoring the lone pair) is 'see-saw'.
5. Step 5: Understand that the lone pair occupies an equatorial position to minimize repulsion, causing the molecule to adopt a see-saw shape rather than trigonal bipyramidal or square planar.